Efforts have been on generation of hybridoma antibodies directed against the hapten p-azophenylarsonate. Twenty such hybridomas have been generated and their amino acid sequence is underway. Idiotype assays have been developed which separate the hybridoma products into those which bear the arsonate cross-reacting idiotype from those which do not. Structural comparisons between idiotype positive hybridomas and the serum idiotype positive material are underway. Efforts are being directed toward identification of a T-cell product which bears arsonate specificity.